generic framing procedure (gfp) for ng-sonet/sdh:...

Generic Framing Procedure (GFP) for NG-SONET/SDH: An Overview

Enrique Hernandez-ValenciaLucent Technologies

IEEE SeminarsJuly 11, 2002

Lucent TechnologiesEnrique Hernandez-Valencia; July 2002, 2002

IEEE Seminar 2002GFP Overview;

Outline

What is GFP?

Problem Statement

GFP Value Proposition

GFP Model- Frame Structure- Procedures

GFP Performance

Applications: – Hybrid SONET/DATA NEs

Summary



Generic Framing Procedure - GFPGeneric Framing Procedure - GFP

A “generic” mechanism to adapt multiple client traffic types as either:

• a physical link (Layer 1) client• a logical data link (Layer 2) client

into a bit synchronous or octet-synchronous transmission channel



Outline

What is GFP?

Problem StatementGFP Value PropositionGFP Model- Frame Structure- Procedures

GFP PerformanceApplications: – Hybrid SONET/DATA NEs

Summary



The Problem: Public Multi-Service Transport

The Problem: Public Multi-Service Transport

Data (IP, IPX, MPLS, etc.) SANs

Fiber or WDMFiber or WDM

OTNOTN

Video

Fibr

e C

hann

el*

ES

CO

N*

FIC

ON

*

DV

B A

SI*

Private Lines

Voice

SONET/SDHSONET/SDH

Applications

Networking

Transport Channels

MACs

Circuits

Ethernet*

RPR

How to support multiple traffic types over the existing transport network infrastructure?How to support multiple traffic types over

the existing transport network infrastructure?

* May also run directly on fiber



The Solutions:A Fragmented Solution Space

The Solutions:A Fragmented Solution Space

X.86

Data (IP, IPX, MPLS, etc.) SANs

Fiber or WDM

ATM

OTN

Video

Fibr

e C

hann

el*

ES

CO

N*

FIC

ON

*

DV

B A

SI*

Private Lines

Voice

HDLC

SONET/SDH

POS

GFP

Application Services

Networking Services

Transport Services

Transport Channels

MAC Services PPP

FRCircuit Services

Ethernet*

RPR

* May also run directly on fiber



Ethernet in “HDLC-like Framing”– Non-deterministic transport overhead– Byte stuffing interferes with QoS/bandwidth management– Flag-based delineation computationally expensive as speed increases

Example 1:Ethernet over LAPS (ITU-T X.86)

Example 1:Ethernet over LAPS (ITU-T X.86)

Flag

1 Byte

LAPS Frame

Etherneton LAPS

HDLCAddress1 Bytes

HDLCControl1 Bytes

Flag

1 Byte

LAPSFCS

4 bytes

LAPSSAPI

2 Bytes

Ethernet Frame

64-1500 Bytes

Byte Stuffing needed!0x7E => 0x7D5E0x7D => 0x7D5D

Ethernet Frame

SONET/SDHSPE

LAPS over SONET/SDH

(X.86)

Transport CapacityCap

acity

Time

Excess traffic

Optimal min. bandwidth



LLC

3 bytes

Example 2:Ethernet over ATM (IETF RFC 1483)

Example 2:Ethernet over ATM (IETF RFC 1483)

Ethernet over ATM– Excellent QoS management capabilities– Large transport overhead for small packets– SAR expensive for simple connectivity services

Etherneton AAL5

Segmentation & re-assembly (SAR)

needed!SONET/SDH

SPE

ATM over SONET/SDH

(G.707)

ATM/AAL5 Frame

48 bytes

48 bytes

48 bytes

48 bytes

48 bytes

48 bytes

48 bytes

48 bytes

48 bytes

48 bytes

48 bytes

48 bytes

OUI

3 bytes

Ethernet Frame

64-65527 bytes

Padding

0-47 bytes

PID

2 bytes

FCS

4 bytes

UU/CPI &Length4 bytes

Ethernet Frame


acity

Time

SAR overhead




Ethernet over GFP– Deterministic transport overhead– No adaptation interference with QoS/bandwidth management – Low complexity frame delineation that scales ups as speed increases

Example 3:Ethernet over GFP-F (ITU-T G.7041)

Example 3:Ethernet over GFP-F (ITU-T G.7041)

Core Header

4 Bytes

GFP Frame

Etherneton GFP

PayloadHeader

4 Bytes

Ethernet Frame

1500 Bytes

No Byte Stuffing orSAR

needed!

Ethernet Frame

SONET/SDHSPE

GFP over SONET/SDH

(G.707/G.7041)

Etherneton GFP


acity

Time

No excess traffic




Outline

What is GFP?Problem Statement

GFP Value PropositionGFP Model- Frame Structure- Procedures


Summary



Why GFP?Why GFP?

Simple and scaleable– Proven technology at 1G, 2.5G and 10G– Scalable beyond 40G

Supports both Layer 1 and Layer 2 traffic

– Alternative transport mechanism to ATM (ITU-T I.341.1/IETF RFC 1483) – Alternative transport mechanism to HDLC-framing (ISO-3309/IETF RFC

2615)

Standards based:

– ITU-T G.7041(2001) & ANSI T1.105.02 (2002)– Endorsed by IETF (RFC 2823) – Endorsed by RPR WG (IEEE 802.17)



Sample ApplicationsSample Applications

Channel Types:

Bit-Synchronous Channel:– Dark Fiber– WDM

Octet-Synchronous Channel:– SONET (T1.105.02)– SDH (ITU-T G.707)– OTN (ITU-T G.709)

Client Types:

Physical Coding (Layer 1):– Fibre Channel– FICON– ESCON– Gigabit Ethernet– Infiniband– DVB ASI

Data Links (Layer 2):– PPP/IP/MPLS– Ethernet– MAPOS– RPR



Outline

What is GFP?Problem StatementGFP Value Proposition

GFP Model- Frame Structure- Procedures


Summary



Functional ModelFunctional Model

GFP – Common Aspects(Client Independent)

GFP – Client Specific Aspects(Client Dependent)

Eth

erne

t

IP/P

PP

Oth

er

Clie

nt

Sig

nals

FCOTN ODUk PathSONET/SDH Path

FIC

ON

ES

CO

N

MA

PO

SFrame Mapped Transparent Mapped

RP

R



Frame TypesFrame Types

GFP Frames

Client Frames Control Frames

Client Data Frames

Idle FramesClient Management

Frames

OA&M Frames(under study)

Client Payload Transfer

Client Traffic

Management

IdleTimeFills

Link OA&M



Generic Frame StructureGeneric Frame Structure

0-60 Bytes of

Extension Headers(Optional)

PayloadInformation

Fixed LengthN x [536,520]

orVariable Length

Packets

Payload FCS

Payload Header

Byte Transmission

Order

Bit Transmission Order

PayloadArea

Payload Length MSB

Core HEC LSB

Payload Type LSB

Payload Type MSB

Type HEC MSB

Type HEC LSB

Payload FCS

Payload FCS MSB

Payload FCS

Payload FCS LSB

Spare

CID

Extension HEC MSB

Extension HEC LSB

UPI

PTI EXIPFI

0x00 (0xB6)

0x00 (0x31)

0x00 (0xE0)

0x00 (0xAB)

Client Data Frames

Client Control Frames

Linear ExtensionHeader shown

(others may apply)

Idle Frame (scrambled)

Payload Length LSB

Core HEC MSB

Core Header



PayloadHeader

4 Bytes

pFCS32 bits

Basic GFP Frame FormatBasic GFP Frame Format

PLI := Payload Length Indicator

cHEC := Core Header CRC (ITU-T CRC-16)

Payload Area := Framed PDU (PPP, IP, Ethernet, etc.)

Payload Header := Client PDU management

pFCS := Optional Payload FCS (ITU-T CRC-32)

PLI16 bits

cHEC16 bits

Payload Area4~65,535 bytes (framed PDU)

GFP Frame

GFP Frame

GFPFrame

PayloadArea

PayloadFCS

CoreHeader



Frame Structure:Summary

Frame Structure:Summary

All GFP OAM&P functions handled via the GFP Core Header

Payload Header supports any payload specific adaptation functions– Client types (Ethernet, IP, MPLS, Fibre Channel, etc.)– Client multiplexing (via Extension Headers)– Client link management (via Client Management Frames)

Optional Payload FCS on a per frame basis

Asynchronous rate adaptation via Idle Frames



GFP ProceduresGFP Procedures

Frame Delineation

Frame/Client Multiplexing

Adaptation Modes

Scrambling– Core Header– Payload Area

Error Handling– Headers– Payload

Client Management



Frame Delineation:GFP State Machine

Frame Delineation:GFP State Machine

HuntState

Pre-SyncState

SyncState

2nd cHECmatch

No 2ndcHEC match

cHECmatch

Non Correctable Core Header

Error

No cHECmatch

CorrectableCore Header

Error

Octet-by-OctetCore Header

Correction Disabled

Frame-by-FrameCore Header

Correction Disabled

Frame-by-FrameCore Header

Correction Enabled



Frame DelineationAn Example

Frame DelineationAn ExampleTwo consecutive cHEC field matches vs. computed CHECPointer-based (PLI field) offset to next incoming frame

PayloadAreacH

EC

PLI Payload

AreacHE

C

PLI Payload

AreacHE

C

PLI

cHEC Fail

CRC Valid

cHEC Match

cHEC Fail

cHEC Fail

cHECPLI

cHECPLI

cHECPLI

cHECPLI

Octet or Bit synchronous stream

PLI Bytes

cHEC Match

Hunt State

Hunt State

Pre-Sync State

Sync State

cHECPLI cHECPLIPLI Bytes PLI Bytes



MultiplexingMultiplexing

Frame Multiplexing via PTI field:– Client Data Frames have priority over Client Mgmt. Fames– Client Management Frames have priority over Idle Frames

Client Multiplexing via Extension Headers:– Null Extension Header on dedicated transport channels per client– Linear Extension Header (point-to-point configurations)– Ring Extension Header (ring configuration)

Spare

CID

Extension HEC MSB

Extension HEC LSB

0-60 Bytes of

Extension Headers(Optional)

Payload Type LSBPayload Type MSB

Type HEC MSBType HEC LSB

UPI

PTI EXIPFI

Linear ExtensionHeader shown

(others may apply)

PayloadArea

Core Header

Payload Header

Frame Muxing:PTI: Payload Type Id

Client Muxing:EXI: Extension Hdr ID

CID: Customer ID



Adaptation Modes: Frame-Mapped GFP

Adaptation Modes: Frame-Mapped GFP

1-to-1 mapping of L2 PDU to GFP payloadUPI field indicates L2 PDU typeExample: IEEE 802.3/Ethernet MAC frames

Payload Header

4 Bytes

cHEC

2 Bytes

PLI

2 Bytes

Core Header

Ethernet Frame

0 -65531 Bytes

GFP- F Frame

Payload Area



Adaptation Modes: Transparent-Mapped GFP

Adaptation Modes: Transparent-Mapped GFP

N-to-1 mapping of L1 codewords to GFP payloadExample: 8B/10B codewords

F C S ( O p t i o n a l

4 B y t e s

P a y lo a d H e a d e r

4 B y t e s

c H E C

2 B y t e s

P L I

2 B y te s

C o re H e a d e r

8 x 6 4 B / 6 5 B + 1 6 S u p e r b l o c k s

G F P -T F r a m e

P a y lo a d A r e a

G F P F C S

# 1 # 2 # N - 1 # N

6 4 B / 6 5 B S u p e r b l o c k

(F la g b its c a r r i e d i n l a s t o c t e t o f t h e s u p e r-b lo c k )

1 | C C L # 1 | C C I # 1

N | C C L # n | C C I # n

D C I # 1

D C I # 8- n

6 4 B /6 5 B b l o c k ( m i n u s F l a g b i t )

6 4 B / 6 5 B # 1 6 4 B / 6 5 B # 2

6 4 B / 6 5 B # N- 1 6 4 B / 6 5 B # N

F 1 | F 2 … | F 8 C R C - 1 6 M S B C R C - 1 6 L S B



Scrambling:DC Balance & Payload Scrambler

Scrambling:DC Balance & Payload Scrambler

Header (PLI Field + CHEC) XOR’d with the 32 bit value “0xB6AB31E0” before transmission for DC balance.

Payload scrambled with ATM-style self-synchronous scrambler

PLI cHEC Payload

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? ?

TransmissionChannel

+ “x43+1“Scrambler

D42

+D0 D1 ...

0xB6AB31E0 +



Error HandlingError Handling

Multi-bit Error Detection & Correction:– Core Header – cHEC (ITU-T CRC-16): – Payload Type Field – tHEC (ITU-T CRC-16)– GFP-T payload (Optimized CRC-16)

Multi-bit Error Detection:– Payload Extension Header – eHEC (ITU-T CRC-16)– Payload Information Field – pFCS (ITU-T CRC-32)

1-bit error correction

3-bit error correction



Client ManagementClient Management

Client Signal Fail (CSF) indications sent periodically upon detection of a failure/degradation eventCleared by new Client Data Frame or CSF timeout

•Loss of Signal (LOS)•Loss of Client Character Sync (LCS)

– Loss of clock/frame– Running disparity violations

•Loss of Signal (LOS)•Loss of Client Character Sync (LCS)

– Loss of clock/frame– Running disparity violations

CSF

Client Signal Fail:•LOS•LCS

GFP Link



Outline

What is GFP?Problem StatementGFP Value PropositionGFP Model- Frame Structure- Procedures


Summary



Performance:Synchronization Loss Events

Performance:Synchronization Loss Events

Re-sync required whenever cHEC test failsLow synchronization loss probability for typical fiber BERExample: 40Bytes PDU at 40G. Loss event frequency decreases with increasing PDU size or decreasing BER

BER Prob [Sync Loss] Frequency

10 -7 5x10-12 ~ 48 min

10 -8 5x10-14 ~ 3.3 Days

10 -9 5x10-16 ~ 1 Year

10-10 5x10-18 ~100 Years



Performance:Missed Frame Delineation Events

Performance:Missed Frame Delineation Events

Low probability of frame unavailability after LOF events Essentially insensitive to random errors for practical BERs

1.E-08

1.E-06

1.E-04

1.E-02

1.E+001.00E-02 1.00E-03 1.00E-04 1.00E-05 1.00E-06 1.00E-07 1.00E-08 1.00E-09

BER

Prob

abili

ty of

Nex

t Fra

me U

nava

ilabi

lity

40

64

128

256

384

512

1024

2048

3072

4096

8192

16384

32768

65535

Frame Size

Typical Ethernet Operational

Range



Performance:Mean Time To Frame

Performance:Mean Time To Frame

Datalink syncs after 2 consecutive cHEC matchesFast Mean Time to Frame (MTTF) delineationLargely insensitive to BER & line rate over the region of interest for (first order approximation)

1.50

1.75

2.00

64 128 256 384 512 1024

2048

3072

4096

8192

16384

32768

65535

GFP Frame Size (Octets)

MT

TF

(PD

Us)

Typical Ethernet

Operational Range



Outline

What is GFP?Problem StatementGFP Value PropositionGFP Model- Frame Structure- Procedures- Performance

Applications: – Hybrid SONET/Data NEs

Summary



Hybrid Network ElementsNG SONET/Data Systems

Hybrid Network ElementsNG SONET/Data Systems

Three basic building blocks– GFP (ITU-T G.7041/ANSI T1.105.02)– Virtual Concatenation (ITU-T G.707/ANSI T1.105.02)– LCAS (ITU-T G.707/ANSI T1.105.02)

Native Interfaces:

• FE• GbE• PPP/IP/MPLS• Fibre Channel• FICON• ESCON STS-n-Xv (OCh-n-Xv)

PHY

LCAS

RepeaterGFP

Encap-sulation

1

2

3

X

PHY

LCAS

Repeateror

Store &

Forward Fabric

GFPAdaptation

STS-n’s(Och-n’s)

1

2

3

X

(G)MII SPI-3/4



Hybrid Network Elements Virtual Concatenation

Hybrid Network Elements Virtual Concatenation

Multiple SONET STS-Nc’s (VC-n’s) grouped into single STM-N-Xv Virtual Concatenation Group (VCG)– Component STS-Nc’s may be routed separately– Compensates differential network delays up to 32 ms

Network Operator provisions no. of channels (X) in VCG– Solves SONET/SDH & OTN bandwidth “granularity problem”

Completely transparent to intermediate NEs. – Only termination nodes need to support this feature



Hybrid Network Elements Virtual Concatenation - Example

Hybrid Network Elements Virtual Concatenation - Example

Public Network

VC-n-Xv or

STS-n-Xv VCG

Hybrid Network Element

VC-n-Xv or

STS-n-Xv VCG

Hybrid Network Element

Legacy Add/Drop Multiplexer

Legacy Broadband X-Connect

Vir

tual

C

onca

tena

tion

Vir

tual

C

onca

tena

tion



Hybrid Network ElementsLink Capacity Adjustment Scheme (LCAS)

Hybrid Network ElementsLink Capacity Adjustment Scheme (LCAS)

Controls hitless addition/removal of STS-N’s (VC-n’s) to/from VCG under management control– In-service hitless bandwidth modification– Address the dynamic management of bandwidth for data transport

services over SONET/SDH

Manages automatic removal/addition of failed/repaired STS-N’s from/to VCG

Supports virtual channel protection through “load sharing” on STS-N’s– Works best on point-to-point links

ITU-T Recommendation G.7042 / ANSI T1.105.02



GFP, Virtual Concatenation & LCASTransport Efficiency

GFP, Virtual Concatenation & LCASTransport Efficiency

SONET SDH

Contiguous Virtual Contiguous Virtual

STS-1 (20%)

VT-1.5-7v (89%)

VC-3 (20%)

VC-12-5v (92%)

STS-21c (85%)

STS-1-18v (95%)

VC-4-16c (35%)

STS-3c (67%)

STS-1-2v (100%)

VC-4 (67%)

VC-3-2v (100%)VC-12-46v (100%)

STS-6c (66%)

STS-1-4v (100%)

VC-4-4c (33%)

VC-3-4v (100%)VC-4-2v (66%)

TrafficType

10Mbps Ethernet

1Gbps Fibre Channel

100Mbit/s Fast Ethernet

200Mbit/s (ESCON)

1Gbit/s EthernetSTS-24c (83%)

STS-1-21v (92%)

VC-4-16c (42%)

VC-4-7v (95%)

VC-4-6v (95%)



Outline

What is GFP?Problem StatementGFP Value PropositionGFP Model- Frame Structure- Procedures

GFP PerformanceApplications:– Hybrid WDM/TDM/DATA NEs

Summary



SummaryGFP Advantages

SummaryGFP Advantages

Versatility: Enables transport services for either Layer 1 or Layer payloads: – PPP, IP, MPLS, Ethernet, HDLC & MAPOS at Layer 2– Fibre Channel, FICON, ESCON, Infiniband, DVB ASI at Layer 1– Endorsed by multiple communities including IEEE RPR WG & IETF

Scalability: Demonstrate transport capabilities at rates from 10Mbps to 10Gbps (and soon beyond)

Simplicity: Eliminates need for ATM and HDLC networking for simple connectivity services resulting in more efficient, lower-risk component designs

Component availability: Broader user demand expected to drive future applications, feature maturity, interface commonality and lower cost



GFP Characteristics and BenefitsGFP Characteristics and Benefits

Simple Header Error Control (HEC) based synchronization:– Generalizes ATM’s HEC synchronization (inexpensive table lookup)– Supports variable or fixed length packets (IP/Ethernet datagrams, block

codes or ATM cells)

Simple pointer-based frame delineation:– Low processing complexity without payload expansion– Low (deterministic) adaptation overhead– High data link efficiency (scalable to 10Gbps and beyond)– Amenable to strict/loose QoS support, particularly for real-time services

Flexible traffic adaptation modes:– Frame-Mapped GFP (GFP-F): Suitable for elastic applications– Transparent-Mapped GFP (GFP-T): Suitable for in-elastic applications

generic framing procedure (gfp) for ng-sonet/sdh:...

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